Spycraft is at its heart part of the general d20 SRD inspired RPG explosion. It's too different from either D&D or d20m to be considered "compatible".

Core mechanics is d20 roll high, with six ability scores, and it has base classes and two tiers of prestige classes. The most notable new features are:

* Each Base class has a specific class feature (called "core abilities") that are only available if that was your class at 1st level.
* Damage system is radically reworked (still digesting it, but appears to be a vitality and wounds inspired mechanic)
* Humans, rather than bonus skills and feat, get a package which represents a set package of bonuses. The exact method of selecting this depends on which specific game is considered. Broadly speaking, it corresponds to a d20 Modern background, but with a little extra, and better balanced. Somewhat annoyingly, there is no similar background origin mechanic for demi-humans, whose race replaces this extra detail entirely.
* Action points (called action dice here) are a major part of the system, and are used to activate critical hits. The GM also has a pool of action dice, which can be used to activate a PC's critical fumble (or an enemy's critical hit).
* The names of skills and feats, and the prerequisites, are completely reworked.
* Iterative attacks are gone, although certain feats replicate their effects. The design feature/flaw of "fight or move" for melee classes is gone.
* Spellcasting seems to be radically changed (still digesting this).
* There is an optional "campaign qualities" system, which changes the way the game works at a fundamental level (sort of like many optional rules in GURPS).

Emma Rome, otherwise known as Ashtagon
Overall site admin for The Piazza. My moderator colour is pink!

Spycraft is at its heart part of the general d20 SRD inspired RPG explosion. It's too different from either D&D or d20m to be considered "compatible".

Core mechanics is d20 roll high, with six ability scores, and it has base classes and two tiers of prestige classes. The most notable new features are:

* Each Base class has a specific class feature (called "core abilities") that are only available if that was your class at 1st level.
* Damage system is radically reworked (still digesting it, but appears to be a vitality and wounds inspired mechanic)
* Humans, rather than bonus skills and feat, get a package which represents a set package of bonuses. The exact method of selecting this depends on which specific game is considered. Broadly speaking, it corresponds to a d20 Modern background, but with a little extra, and better balanced. Somewhat annoyingly, there is no similar background origin mechanic for demi-humans, whose race replaces this extra detail entirely.
* Action points (called action dice here) are a major part of the system, and are used to activate critical hits. The GM also has a pool of action dice, which can be used to activate a PC's critical fumble (or an enemy's critical hit).
* The names of skills and feats, and the prerequisites, are completely reworked.
* Iterative attacks are gone, although certain feats replicate their effects. The design feature/flaw of "fight or move" for melee classes is gone.
* Spellcasting seems to be radically changed (still digesting this).
* There is an optional "campaign qualities" system, which changes the way the game works at a fundamental level (sort of like many optional rules in GURPS).

Thanks for providing these details. Looking at the Wikipedia it looks like Spycraft 1st Ed is much closer to the SRD than Spycraft 2.0 however?